Kesha Hits the Red Carpet for the First Time Since Rehab
03/30/2014 AT 01:40 PM EDT
The singer, 27, attended the Humane Society of the United State's 60th anniversary benefit gala in Beverly Hills, and posed for photos in a sheer black floor-length gown and her signature multi-colored hair, chopped into a wavy bob.
"She was clearly enjoying being back on the red carpet," says an onlooker. "She looked great … very healthy."
Since leaving rehab earlier this month, Kesha has made some changes, like updating her Twitter handle, dropping the dollar sign from her name and severing ties with those who don't encourage her wellness.
"She has eliminated all of the negative people and influences in her life," a friend of the pop star told PEOPLE. "She has surrounded herself with only supportive and loving friends and family."
"She's doing great. She looks and feels fantastic," a friend says.
The singer delayed her tour in February while she continued treatment at a Chicago-based facility, after beginning treatment for anorexia and bulimia in January.
Reporting by MELODY CHIU